Vehicle cargo containers for transporting bulk material such as sawdust, gravel chip, cutter shavings and the like typically include open top boxes such as semi-trailers or the like defining side walls, a front wall, a rear wall and a floor. These open top containers are typically mechanically coupled to various types of vehicles such as cargo ships, railway carts and truck cabins for transporting goods between various locations.
During transportation in these so-called open top containers, there exists a substantial risk that a portion of the load may be blown out of the open top container by various physical phenomena such as vibration, aerodynamically created vacuum, wind or the like. If some of the load is accidentally blown out of the container it may potentially not only cause unnecessary wastage of the transported goods but may also create a dangerous situation.
For example, when the open-top container is attached to a truck cabin, some of the load accidentally blown out of the container may contaminate the road or highway as it whirls around thus causing dangerous ground road conditions. It may also be blown directly towards the windshield of following vehicles creating a potentially disastrous situation.
Accordingly, in many areas, regulations have been implemented for the carriage of various loads, particularly on public highways requiring that open top containers be provided with some type of covering structure for covering the loading aperture during transport. With the increasing number of accidents, these official requirements have become more and more stringent, sometimes requiring adequate coverage for the load on even short journeys.
Consequently, there has been an industry wide move to provide permanently installed flexible covers often referred to as tarpaulins or tarps that can be quickly rolled and unrolled by the driver so as to respectively allow selective uncovering and covering of the load. When these permanently installed tarpaulins are used only occasionally they may be stored on the vehicle in a folded condition and unfolded over the body as and when required.
Various configurations of tarpaulins have been proposed. However, two configurations have proven to be particularly popular. One such configuration is the so called end-rolled tarpaulin which is gathered at one of the longitudinal ends of the container when not in use and moved along the body of the container between operative and stored positions.
The end-rolled tarpaulins are typically gathered at the front end of the vehicle and are usually provided along their length with a number of transverse supporting bars which extend between the two longer side walls of the container. The end-rolled tarpaulins are typically moved by means of a pair of cables trained over pulleys and carrying the tarpaulins with them as they move. With such an arrangement, the movement of the tarpaulin typically moves the bows automatically out of the way so that the latter do not obstruct the re-loading through the top opening. The movement of the bows out of the way also reduces the risks of having the latter damaged by a new load.
The other type of permanently installed tarpaulins preferred by some haulers is commonly referred to as a side-load tarpaulin. The side-load tarpaulins typically, permanently extend the full length of the container body and are rolled and unrolled about a so-called rolling rod that also typically extends the full length of the container body.
Rolling the tarpaulin around the rolling rod may cause the formation of folds in the tarpaulin, as the tarpaulin is typically not stretched during this operation. These folds cause the rolled tarpaulin to take a relatively large amount of space around the rolling rod as the folds create gaps in the rolled tarpaulin.
In addition, the folds induce mechanical stresses in the rolled tarpaulin, which reduces the useful life of the tarpaulin as the tarpaulin may then be weakened. In some cases, if a tarpaulin including a fold is rolled relatively tightly around the rolling rod, the tarpaulin may even be torn at the fold location.
Against this background, there exists a need in the industry to provide a novel device for maintaining a tarpaulin in a taut state.
An object of the present invention is therefore to provide a device for maintaining a tarpaulin in a taut state.